Technological Field
The present invention relines to a charging device and an image forming apparatus. The image forming apparatus includes an electrophotographic device, a recording device, a display device and the like such as a digital copier, a facsimile and a printer, irrespective of whether color or monochrome.
Description of the Related Art
In an image forming apparatus, a photoreceptor dram serving as a member to be charged is charged in advance to prepare a charged surface, which is subjected to exposure, thereby discharging the electric charge on the exposed portion to form an electrostatic latent image, which is then subjected to processes such as development, transfer onto a transfer paper sheet and fixing, with the result that an image is formed on the transfer paper sheet.
The method used for causing the photoreceptor drum to become charged is as follows. Specifically, a charging device formed of a blade, a brush, a charging roller and the like is used for the photoreceptor drum. The charging roller is brought into contact with the photoreceptor drum, so that the photoreceptor drum becomes charged.
As a charging roller, a thin-layer charging roller has been commonly used. This thin-layer charging roller is a charging roller that is obtained by directly applying a thin conductive layer onto a cored bar. This thin-layer charging roller can be reduced in cost as compared with the conventional thick charging roller having an elastic layer. This thin-layer charging roller has a simple configuration in which only a thin protective layer is provided on the cored bar member. Such a thin-layer charging roller is disclosed in Japanese Laid-Open Patent Publication No. 08-44141.